Process and apparatus for making pulp from fibrous material



- June 28 1927.

Phoczss AND APPARA'rus FQMAAKIN PULP Pam: FIBROUS MATERIAL Original Filed July 1925 1 6 i ii: 5

MT g'! g 4: i

ATTORNEYS.

15 and collect-in the space,above the cooking ide a process and containin ,Valve means of the connection 11.

- FREDERICK-K. rrsrr; in,

TES- PATE- 1,633,732 1 NT OFFICE,

OF- SAN FRANCISCO, CALIFORNIA.

rnocnss AND APPARATUS ron' MAKING PULP rnou ruinous MATERIAL.

Application filed July 14, 1925, Serial This invention relates to a process and apparatus for making pulp from fibrous material and is particularly directed to the circulating ot-the medium used for the treatment of the material in a digester.

There are many known processes for the production of pulp by the treatment of fibrous material in a digesterwith various types of cooking. liquor, and this invention is applicable to many or all of them but particularly to the sulphite process in which the S0 gas and solvent volatile extractives, 5

which are liberated from the material under treatment and form the cooking liquor ved from the digester, cooled liquor, are remo and are of no further vuse and separated; in the cook.

The chief object of this invention is to proapparatus for bringing the cooking'liquor, preferably mixed with gases and volatile substances which accumulate above the liquor and material under treatment, into intimate and continuously or periodically renewed contact with the material in the digester in the same cook.-

A further object is to provide a process and means for continuously or periodically withdrawing a portion of thetreating medium from the upper part of the digester and returning it to the lower part of the digester to cause circulation therein.

The invent'on will best be understood by reference tothe accompanying drawing, in

which a preferred form of the apparatus is shown in elevation with a portion in section.

In the drawing, 1 represents a digester of the usual type. The lower end of a pipe 2 3 is connected to the bottom conical portion of the digester at a tangent to the surface of this portion 0 the digester. A steam ejector 4 of any suitable type is connected to the upper end of the'pipe 2 and the pipe 5 containing the valve 6 connects the ejector with the digester;

at a point below the liquor level therein. screen 7 prevents the admission of the fibrous material to the pipe 5. The space in the digester above the charge and liquor level is connected with the pipe 2, at a point below the ejector, by means of a pipe 8 having a valve 9 and perforated screen 10. Steam' under pressure is admitted to the ejector by of my invention circula- In the operation alone or mixed, with the tion of the liquor,

vafter it has p f of the liquor and A that this is not only ens the liquor, and the benefit of the so]- m. 43,595; Benewcd as 24, 1927.

gases and volatile extractives contained in the space above the liquor in the digester,; is effected continuously or periodically as desired. To circulate theliquor alone, steam is admitted to the ejector and the valves 6 and 3 are opened whereby liquor is withdrawn from the upper part of the digester, enetrated through the charge of-materiahand is forcedthrough the pipe 2 into the lower conical part of the digester. The liquor leaving the pipe 2 is given a swirlingupward motion owing to the manner in which the pipe enters the lower conical portion of the digester and this upward circulation agitates the charge and brings the liquor into renewed and intimate contact; with the particles of material under treatment to remove the encrusting material and liberate the fiber. When it is desired to circulate the gases and -volatile' solvent extractives from the space in the digester above the 1naterial, the valve 9 is opened and these gasesand vapors are drawn from the digester and forced into pipe 2 by the steam from the ejector being there mixed with the withdrawn'liquor and again returned to the digester in the manner specified. Y

Moreover, itmay' sometimes be desirable tocirculate only the gases and volatile solvent extra'ctives from'the top of the digester, and this is accomplished with valve 6 closed and valve 9 and the rest of the circuit open. In the process of making pulp it is of importance that the treating liquor be intimately in contact not only with the material, but with the interior of the material. While it is true the material is submerged in the liquor, the fact remains that the gases, vapors and the stronger part the extractives from the wood rise to the top of the digester. In many instances in known processes the accumulation at the top of the digester is blown ofi to the atmosphere, but I have discovered a waste, but it weakvent extractives in variousforms for enriching the liquor is lost. I have also discovered that it is poss'ble to save the vapors and extractive's from the chips or the like, and so introduce them to the liquor as to materially enrich the latter to better and more quickly act on the chips in the process of digesting or cooking the pulp. With this end in view it is evident that by the,

,. thel'ooiis ll qllor in the digester b employment of the injector the gases, vapors or li uor at the top of the digester can be with rawn and introduced to the bottom of the body of liquor and again act on the material in the digester. The gases and liquor from the top of the digester are intermixed. with the solvent extractives liberated from the chips, which through action or reaction, whether chemical or physical, with the reagent employed, acts materially to shorten the process and is less expensive than processes now in use. The swirling action of the liquor at the bottom of the digester and the ebullition of the liquor creates agitation in the digester, with the result that the liquor impregnates the chips and complete treatment of the constituents assured. I claimb 1. The process of making pulp from fibrous material in a digester, consisting in cooking the material in' a heated liquor under pressure and with a space above the body of said liquor, withdrawing gases and volatile extractives from .said space and liquor from the upper portion of the body of means of steam under pressure, mixing t e ases and volatile extractives with the with rawn liquor and returning the mixture to the lower portion of the digester for use in the same cook.

he process of making pulp from fibrous material in a digester, consisting in cooking the material in a heated liquor under pressure, withdrawing by means of steam under pressure, a portion of the liquor from the upper part of the digester, returningsaid portion of liquor to the lower part of the digester and imparting to said liquor a swirling motion within the digester.

3. The process of making pulp from fibrous material as claimed in claim 1, wherein the circulation of gases, volatile extractives and liquor is intermittent in order to pulp from fibrous material, consisting of a digester in combination with an ejector adapted to remove gases, volatile extractives, and liquor from the upper portion of the digester and return the same thoroughly mixed to the lower portion of said digester.

6. An apparatus as defined in claim 5, having means for imparting to the liquor returnedto the lower conical portion of the digester a swirling motion.

An apparatu'sfor making pulp from fibrous material, consisting of a digester, an external connection between the upper and lower portions of said digester, a steam ejector in said connection, the upperend of said connection having two branches, one connected with said digester at a point below the liquor level therein and the other at a point above the said liquor level and the lower end of said connection being-- adapted to discharge liquor flowing there through at a tangent to the internal surface of the lower conical portion of said digester.

8. An apparatus .as defined in claim 7, wherein the second is joined to the external connection at a point below the union with the first mentioned branch pipe.

In testimony whereof I aflix my signature.

' FREDERICK K'. FISH, JR.

mentioned branch pipe 

